b Chapter 31- Diffraction and Interference 31.1 Huygens' Principle
Christian Huygens was a Dutch scientist in the late 1600's. He cam eup with an idea about waves.
-His principle states that wave fronts are made up of smaller wave fronts.
-As a wave front spreads out, it will look as it forms a plane, and less like it forms a curve.
Huygens Principle can demonstrate the lwas of reflection adn refraction.
~If you place something like a ruler into water horizontally, straight waves will be made. If there is a small opening ahead, less of the wave will get through and the wave will become curved. 31.2 Diffraction
The bending of a wave by means other than reflection or refraction.
-The opening is wide compared to the wavelegnth--->spreading effect is small
-The opening is smaller compared to the wavelegnth--->spreading effect is larger
(ALL WAVES)
Light passing through...
a large opening--->sharp shaddow small opening--->fuzzy shaddow
(diffracion occurs in all shaddows, even the sharpest can be blurred at the edges) diffraction fringes- wehn light has one color, its a border around the edge of the shaddow caused by diffraction. [in white light, the fringe will merge to make a blury fringe at the end of the shaddow]
31.3 Interference
Two sets of waves crossing eachothers paths can cause an interference pattern (wave effects are either increased, decreased, or neutralized).
-crests overlap other crest--->effects combine=constructive interference
-crests overlap other trough---> effects combine= destructive interference ripple tanks- tanks of water where water waves are produced in carefully controlled conditions.
when two sources are placed side by side...
-the greater the frequency, the closer the waves. 31.4 Young's Interference Experiment monochromatic light-light of a single color
By Thomas Young in 1801, discovered that when monochromatic light is directed through two closely placed pineholes, fringes of of brightness and darkness are produced on a screen behind. The fringes result from light waves from both holes arriving from crest to crest. The dark areas result from light waves arriving trough to crest.--->demonstrating Hiygens Principle diffraction grating- a multitude of closely spaced parallel slits.
-most commonly seen in reflective materials 31.5 Single- Color Interference from Thin Films
Interference fringes can be produced be light reflection from two surfaces close together.
-monochromatic light shined on two plates of glass that are one atop the other, will show dark bands.
~this resuts from the interferencebetween the waves reflected from the glass on the top and bottom surfaces of the air space between the plates.
EX: a good use is testing of precision lenses. if the tested lens is placed on flat piece of glass and illuminated with monochromatic light, light/dark fringes are seen.
-if there are irregular fringes there is an irregular surface. 31.6 Iridescence of Thin Films iridescence- when colors are produced by the interference of light waves of mixed frequencies in thin films.
-In something such as a film, 31.7 Laser Light
incoherent- light emitted by a common lamp. It has many phases of vobrations and frequencies.
The light is chaotic and and rampant, it spreads out after a sort distance. choerent- a beam of light that has the same freqency, phase, and direction. there are no interference between waves. It is produced by a laser.
laser-light amplification by stimulated emission of radiation. A light wave emitted from one atom stimulates the emission of light from a neighboring atom so the crests of each wave concides. 31.8 The Hologram a three dimensional picture of an object that contains an interference pattern ...
-when light falls on a hologram, it is diffracted by the fringed pattern to produce wav fronts identical on form to the origional wave fronts reflected by the object.
31.1 Huygens' Principle
Christian Huygens was a Dutch scientist in the late 1600's. He cam eup with an idea about waves.
-His principle states that wave fronts are made up of smaller wave fronts.
-As a wave front spreads out, it will look as it forms a plane, and less like it forms a curve.
Huygens Principle can demonstrate the lwas of reflection adn refraction.
~If you place something like a ruler into water horizontally, straight waves will be made. If there is a small opening ahead, less of the wave will get through and the wave will become curved.
31.2 Diffraction
The bending of a wave by means other than reflection or refraction.
-The opening is wide compared to the wavelegnth--->spreading effect is small
-The opening is smaller compared to the wavelegnth--->spreading effect is larger
(ALL WAVES)
Light passing through...
a large opening--->sharp shaddow small opening--->fuzzy shaddow
(diffracion occurs in all shaddows, even the sharpest can be blurred at the edges)
diffraction fringes- wehn light has one color, its a border around the edge of the shaddow caused by diffraction. [in white light, the fringe will merge to make a blury fringe at the end of the shaddow]
31.3 Interference
Two sets of waves crossing eachothers paths can cause an interference pattern (wave effects are either increased, decreased, or neutralized).
-crests overlap other crest--->effects combine=constructive interference
-crests overlap other trough---> effects combine= destructive interference
ripple tanks- tanks of water where water waves are produced in carefully controlled conditions.
when two sources are placed side by side...
-the greater the frequency, the closer the waves.
31.4 Young's Interference Experiment
monochromatic light-light of a single color
By Thomas Young in 1801, discovered that when monochromatic light is directed through two closely placed pineholes, fringes of of brightness and darkness are produced on a screen behind. The fringes result from light waves from both holes arriving from crest to crest. The dark areas result from light waves arriving trough to crest.--->demonstrating Hiygens Principle
diffraction grating- a multitude of closely spaced parallel slits.
-most commonly seen in reflective materials
31.5 Single- Color Interference from Thin Films
Interference fringes can be produced be light reflection from two surfaces close together.
-monochromatic light shined on two plates of glass that are one atop the other, will show dark bands.
~this resuts from the interferencebetween the waves reflected from the glass on the top and bottom surfaces of the air space between the plates.
EX: a good use is testing of precision lenses. if the tested lens is placed on flat piece of glass and illuminated with monochromatic light, light/dark fringes are seen.
-if there are irregular fringes there is an irregular surface.
31.6 Iridescence of Thin Films
iridescence- when colors are produced by the interference of light waves of mixed frequencies in thin films.
-In something such as a film,
31.7 Laser Light
incoherent- light emitted by a common lamp. It has many phases of vobrations and frequencies.
The light is chaotic and and rampant, it spreads out after a sort distance.
choerent- a beam of light that has the same freqency, phase, and direction. there are no interference between waves. It is produced by a laser.
laser-light amplification by stimulated emission of radiation. A light wave emitted from one atom stimulates the emission of light from a neighboring atom so the crests of each wave concides.
31.8 The Hologram a three dimensional picture of an object that contains an interference pattern ...
-when light falls on a hologram, it is diffracted by the fringed pattern to produce wav fronts identical on form to the origional wave fronts reflected by the object.